vi FORM AND FUNCTION 159 



young Partridge has quill feathers big enough to 

 enable him to fly, to some extent, very soon after 

 leaving the egg. These are shed and replaced several 

 times during his first summer and autumn, thus keep- 

 ing pace with his rapid growth. Thrushes, Blackbirds, 

 and Fieldfares have one complete moult in their first 

 autumn. 



Change of Colour without Moulting. 



In spring the cock Gray Linnet becomes the " Red 

 Linnet," and appears with a crown and breast of 

 crimson in place of the dull gray of winter, and 

 yet it is certain that no feathers are shed. In cap- 

 tivity he gradually loses his crimson splendours, which 

 fade to ochre-yellow. After the first moult he assumes 

 and retains the dull plumage of the hen. The fore- 

 head of the Redpoll becomes blood-red and his throat 

 and breast carmine, equally without the shedding of 

 a feather. The nape and back of the Brambling turn 

 from reddish-brown striped with black to pure glossy 

 blue-black without any moult ; and, to take one more 

 instance, the Blackheaded Gull, in the course of a 

 fortnight, dyes the white plumage of his head black, or, 

 more strictly speaking, a very dark brown. In some 

 cases the explanation is perfectly simple ; the crown 

 and breast feathers of the Linnet have wide gray 

 borders which in spring break off and let the crimson 

 that was before covered up become visible. The same 

 is the case with the Redpoll, Brambling, the Snow 

 Bunting, whose back plumage becomes black in spring, 

 and the Blue Throat. In some of these cases Gatke 



